Location estimation plays a valuable role in various applications, such as navigation, target tracking, and emergency services. Wireless devices can supply high positioning accuracy such that users can acquire better location-based services (LBS). Localization of user equipment (UE) has attracted attention in wireless communications after the implementation of Enhanced 911 (E-911) regulations adopted by Federal Communications Commission (FCC). In outdoor and line-of-sight (LOS) environments, a global positioning system (GPS) can provide UEs position with relatively accurate precision through well known the schemes. However, GPS techniques generally do not provide reasonable location estimation accuracy for UE position under non-line-of-sight (NLOS) conditions, especially in heavily obscured environments, e.g., indoor environments, environments with many tall and close buildings, etc.
Long term evolution advanced (LTE-A) wireless communications systems, such as those that use orthogonal frequency division multiple access (OFDMA) technologies to efficiently handle broadband communication, have been proposed to achieve high data rates, high spectral efficiency, and greater capacity in wireless communications networks. To fulfill the rising data communication requirement in indoor environments, the architecture can be adapted into a heterogeneous network (HetNet) which can be adopted in LTE-A systems to include both macro base station (mBS) and femto BS (fBS). Macro base stations and femto base stations forming a HetNet can serve to help mitigate poor connectivity that can occur between a macro base stations and UEs in wireless network that does not include femto base stations. Femto base stations can be include short-range base stations which service UEs. As such, femto base stations can provide wireless network coverage for UEs in indoor environments or other NLOS environments. The development of mBS/fBS HetNet architectures can benefit many applications, such as LBS in indoor environments.